Telephone



(No Model.)

H. V. HAYES -& W. L. RICHARDS. TELEPHONE.

No. 487,219. Patented Nov. 29, 1892..

UNITED STATES PATENT OFFICE.

HAMMOND v. HAYES, or

CAMBRIDGE, AND WILTON L. RICHARDS, OF

OF BOSTON, MASSACHUSETTS.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 487,219, dated November29, 1892., Application filed September 10, 1892- Serial No. 445,558. (Nomodel.)

To ttZZ whom, it may concern.-

Be it known that we, HAMMOND V. HAYES, residing at Cambridge, and WILTONL. RICH- ARDS, residing at Maiden, in the countyof Middlesex,State ofMassachusetts,have invented certain Improvements in Telephones, of whichthe following is a specification.

This invention relates to electric telephones; and its object is toprovide a receiving-telephone capable of being connected with twocircuits at the same time and adapted to receive messages from eitherwithout introducing or facilitating any reciprocal interference betweensaid circuits. Attempts have from time to time been made to devise suchcompound receiving-telephones and have taken the form either ofinclosingina common case two or more bar-magn ets, each separatelyprovided with an inducing-helix for its own circuit and adapted to actupon a common diaphragm, or of providing a single-bar magnet with aplurality of helices, each helix being in a different operating circuit.The results of these attempts have not been satisfactory, for the reasonthat in all such cases it has in practice been found that the apparatushas had a constant and strong tendency to act as a repeatinginduction-coil. In other words, the voice-currents coming over one ofthe circuits and through the telephone-coil of such circuit haveexercised an inductive influence over the coil of the other circuit, andhave thereby caused similar voice-currents to circulate through the saidother circuit, so that messages transmitted over either circuit arerepeated over the other, a result which is extremely undesirable; yetthere is a cons1d erable call for an instrument which will enable anoperator to receive messages or transact business over one circuit whilehe is listening also over another.

By our invention we are enabled to construct such an instrument; and itmainly consists in providing a double-pole magnet for each circuit andin relatively arranging such magnets that they are inductively neutralwith respect to one another, such an arrangement being effectuated bymounting the two magnets, each with its poles on a plane substantiallyat a right angle to the center of the plane of those of the other, thetwo poles of each being practically equidistant from each of the polesof the other-that is to say, if a straight line be supposed to passbetween the centers of the poles of one magnet, it will be perpendicularto a similar line passing between the centers of the poles of the other.

It further consists in mounting these magnets so relatively disposed insuch a way that they face one another, each being furnished with itsowndiaphragm in mounting them on opposite sides of a common centralsupport, recessed on each side to form a vocalizingchamber for eachdiaphragm and in providing the said support with a single earpiecehaving two independent sound-channels, one leading to eachvocalizing-chamber.

In the drawings which illustrate and are a part of this specification,Figure 1 is a perspective View of my compound or double-circuittelephone. Fig. 2 is a section on the line 0c 00 of Fig. 1. Fig. 3 is aside view of the telephone asit has been made, with one of itscap-pieces or magnet-disks and the screw-retaining ring thereof removed;and Fig. 4 is a detail drawing indicating the relative position of thetwo magnets.

The construction of an instrument case which is suitable and convenientcan readily be understood by first considering Figs. 2 and 3. A nucleusor central disk 1, of non-eonducting materialsuch as hard rubber,vulcanized fiber,or hard woodis provided,which is hollowed out on bothsides to form a circular recess or chamber 8, having a peripheralboundary flange 2, and within this flange on both sides a shoulder ordiaphragm-seam. A deeper space 10 of any suitable form (the circularform being convenient) is further made in the bottom of each chamber, asshown in plan in Fig. 3 and in cross-section by Fig. 2; and from a pointin the side of each of these deeper recesses a sound channel on leadsthrough the peripheral wall of the central disk below thediaphragm-seat, whereby the air vibrations, acting to reproduce soundsfind egress, the two sound-channels being sepa rated by the partition11. A suitable neckpiece it, similarly perforated with continuationchannels m, is atfixed to the exterior of the disk 1 at the point whereit is pierced by the said sound-channels, and, if desired, this neck 0%may be formed integral with the central disk; or an additional piece maybe secured thereto by screws or in any preferred way. The neck isexternally threaded at 19, as shown, and an earpiece 12, of ordinaryconstruction and form, is screwed thereon. The diaphragms 9 are, asusual, made of ferrotypeiron, loosely lit within the flanges 2, and areplaced upon the shoulders or diaphragm-seats 2. When in place, they ofcourse inclose flat vocalizingchambers 8 on their front side, whichchambers connect with the outer air only through the spaces 10 andsound-channels 00.

Fig. 4 shows the relative arrangement of the magnets 5, theirpole-pieces 19 p and helices 7 7 The magnets 5 may be mounted behindtheir respective diaphragms in any preferred way, so thattheircoil-surrounded polepieces are fixed in close proximity to thecentral portion of the said diaphragms in amanner well understood,provided that their relative arrangement is such that the two poles ofeach are on a plane which is substantially perpendicular to that onwhich are the two poles of the other, as shown. This may be otherwisestated by saying that a straight line drawn through the centers of thepoles of one of the magnets, and forming a diameter of the diaphragmthereof, must be at right angles with and substantially perpendicular tothe center of a similar straight line drawn through the centers of thepoles of the other magnet and forming a diameter of the other diaphragm.

As already pointed out, in former attempts to construct acompound-circuit telephone it has been found that the operation of onecircuit has inductively acted within the instrument upon the other. Inour improved instrument, in which the poles of the two magnets and theirhelices are placed at substantially a right angle to each other, thisdifficulty is overcome and there is no interference between thecircuits, inductive neutrality being fully achieved. This of course willbe understood by considering that a given pole and helix of each of themagnets is so placed with respect to both poles of the other that anyinduction exercised upon it by either one of the poles of the other isbalanced and neutralized by an equal but opposite induction exercisedupon it by the opposite pole of the other, each pole of either beingsubstantially equidistant from both poles of the other.

In the drawings, the two magnets 5 are of semicircular form, each havingpolar projections projecting diametrically toward the center of thecircle, the diametrical polar projections of one being perpendicular toand bisecting a line drawn through those of the other. Thetelephone-coils 7, connected in series, surround the pole-pieces}; ofone magnet, of which the wires 19 are the terminals, and the coils 7*,having terminal wires (1, surround the pole-pieces p of the othermagnet. In telephones which have been actually made embodying theseprinciples, the construction shown in the drawings has been adopted.Inclosing caps or magnet-supporting disks 4, of hard rubber or likematerial, are provided of such size as to fit snugly within the recessesof the central disk 1, and to rest upon the diaphragm edges, as shown,so that when they are secured they hold the said diaphragms in place.The inner side of the disks 4 are in turn recessed, first, with a widebut shallow recess 21, which may serve as a rear vocalizing-chamber,and, secondly, with a narrower but deeper central recess 6, which servesto inclose and protect the telephone-circuit helices 7 7", ashereinafter explained. The inclosing disks 4 are secured to the centraldisk by means of clamping-rings 3, which screw over the threaded edge ofthe flange 2 thereof and overlap the said inclosing disks. The magnets 5are secured by screws 17 to the outside surface ot the disks 4 and theirpole-pieces p 19 project through holes prepared for them into the deeprecess 6, being sufficiently long to reach to the proper distance fromthe diaphragm. Their helices 7 7 a are slipped over the pole-pieces andproperly connected. The binding-screws 5 form a convenient means forbringing the terminal conductors through the casing, the said terminalsbeing connected therewith in a manner well understood; or, if desired, aflexible conductor 0 or 01 may pass directly into the casing through anaperture in the disk i and connect directly with the helix-terminals.

The clamping-ring attachment aitords a ready means of adjusting themagnets into the desired position of neutrality, and in securing themagnet-holding disks in position they may first be placed by observationin a position where the polar projections are at a right angle with eachother, after which the clamping-ring may be partly screwed up and theinstrument operated. If it be found that the position of neutrality hasnot been fully attained, one of the disks can then be slightly moved ineither direction until a point is found where the operation of one ofthe circuits does not induce upon the other, when the clamping-ringshould finally be tightened up. Our compound telephone is well adaptedfor use as an operators head-telephone, being light and portable. Suchuse is indicated in the drawings, where a portion of springs 15 16,-organized for head-wear, are shown as being jointed to a metal strap 13,secured to the case by the thumb-screw 14.

Having now fully described our invention, we claim- 1. Amagneto-telephone for two circuits, comprising a double-pole magnet andhelices therefor for each circuit, the poles and helices of each magnetbeing arranged in a position inductively neutral to those of the other.

2. A compound or double-circuit telephone having for each circuit anindependent diaphragm and inducing helices and magnet,the poles andhelices of each magnet being arranged substantially perpendicular oratright angles to the poles of the other, whereby reciprocal inductiveneutrality is secured, substantially as described.

3. A compound or double-circuit magnetotelephone provided with anindependent magnet and inducing-coils, and diaphragm for each circuitand having a single and common case and earpiece, each magnet having itspoles and helices so relatively arranged that a straight line unitingits said poles will be substantially perpendicular to a straight linesimilarly unitin gthe poles of the other, whereby the twotelephone-circuits are made relatively neutral, substantially asdescribed.

4. In a telephone, two double-pole magnets, the poles of each beingfitted with inducinghelices adapted for connection, respectively, inindependent circuits, and each magnet being secured in such a positionthat each of its poles is substantially equidistant from the two polesof the other.

5. In a compound or double-circuit telephone, the combination of acentral non-conducting disk having a shouldered recess on each side toform a vocalizingchamber and diaphragm-seat, an earpiece secured to theperiphery of said disk and connecting with the vocalizingchambers on thetwo sides thereof by independent sound-channels, a diaphragm for eachrecess resting by its edges upon the shoulder thereof, closing-caps ormagnet-holding disks for the side recesses of the said central diskadapted to inclose and clamp the edges of the diaphragms, and anindependent bipolar magnet and its inducingcoils for each circuit,secured upon and supported by the said caps or disks, respectively, thetwo magnets being arranged with their poles in close proximity to theirrespective diaphragms, and substantially at right angles to the poles ofthe other, substantially as described.

6. In a compound telephone, the combination of two separate bipolarmagnets provided with pole-surrounding helices, the respective helicesof each being adapted for inclusion in a circuit independent of theother, with means, as indicated, for the angular displacement andadjustment of either magnet relatively to the other, for the purpose ofpreventing reciprocal inductive effects, as described herein.

In testimony whereof we have signed our names to this specification, inthe presence of two subscribing witnesses, this 7th day of September, A.D. 1892.

HAMMOND V. HAYES. WILTON L. RICHARDS. Witnesses:

THOS. D. LOCKWOOD, GEO. WILLIS PIERCE.

